Tool holders of this type are particularly suited for receiving shaving tools having a cylindrical shaft, such as drills, cutters and reaming tools. The recess is thereby usually designed as a chuck or as a collet receiving means. The regulating member which coaxially extends into the recess can be adjusted in a predetermined range to serve as a positioning stop for the axial adjustment of the tool. An adjusting screw is usually used as the regulating member, which adjusting screw can be operated only through the shaft or through an externally accessible recess. To adjust the regulating member, thus either the tool holder must be removed from the spindle or the tool from the tool holder.
It is furthermore known in a tool holder of the above-mentioned type (WO 90/10517) to adjust the regulating member with an adjusting mechanism operable from the outer surface of the base member. The regulating member is supported in the base member and is there constructed so that it has an axially extending cylindrical bolt with a rack section thereon, and a gear mates with the tooth system of the rack section and a clamping element is movable into and out of engagement with the outer surface of the cylindrical bolt. Since the positioning stop is exposed to significant axial forces during the machining operation, there exists the danger that an unwanted axial adjustment occurs when the clamping member provided there is not sufficiently tightened.